1. Field of the Invention
The present invention relates to an image processing apparatus and method, and more particularly, to an image processing apparatus and method for correcting a tomographic image used in ophthalmological diagnosis and treatment.
2. Description of the Related Art
A tomographic image photographing apparatus for eyes such as optical coherence tomography (OCT) is capable of three-dimensional observation of an internal state of a retina layer. This tomographic image photographing apparatus has been receiving attention in recent years because it is useful for accurate diagnosis of a disease.
The tomographic image photographing apparatus splits low coherent light into reference light and measuring light. The measuring light irradiates an object to be inspected, and return light from the object to be inspected and the reference light are caused to interfere with each other so that tomographic measurement of the object to be inspected can be performed. In other words, the measuring light scans the object to be inspected, to thereby obtain a two-dimensional tomographic image (hereinafter, referred to as a tomographic image) or a three-dimensional image (hereinafter, referred to as a volume image) as a set of plurality of tomographic images. However, if the object to be inspected is a living organism such as an eye, a deformation may occur in the volume image due to movement of the eye. Therefore, high-speed measurement with high sensitivity is required.
As one method for this, US 2008/0284981 discloses a method of simultaneously measuring a plurality of points of the object to be inspected. According to this disclosure, light from one light source is split into a plurality of light beams by using a slit. Then, the light beams are separated by a beam splitter into a plurality of measuring light beams and reference light. The measuring light beams irradiate the object to be inspected, and return light beams from the object to be inspected are combined with the reference light by the beam splitter. Then, the plurality of combined light beams enter a grating and are detected simultaneously by a two-dimensional sensor. In this way, according to US 2008/0284981, high speed measurement can be performed by simultaneously measuring with a plurality of measuring light beams.
In addition, Japanese Patent Application Laid-Open No. 2007-130403 discloses a configuration in which one measuring light beam is used, and an image for correction in the direction crossing a main scanning direction of the measuring light is formed when the volume image is generated. Then, the image for correction is used for correcting a deformation of the volume image.
In the configuration disclosed in U.S. Patent Publication No. 2008/0284981, high speed measurement can be performed by simultaneously measuring with a plurality of measuring light beams, but there is no disclosure concerning eye movement. If a volume image is generated, a deformation may occur in the volume image because a positional deviation occurs between neighboring tomographic images due to an influence of the eye movement.
In the configuration disclosed in Japanese Patent Application Laid-Open No. 2007-130403, a tomographic image for correction must be acquired for deformation correction of the volume image.